It is known that many automotive systems are provided with a controller, normally an electronic control unit (ECU), which is configured to perform, among other functions, a “Stop & Start” (or simply S/S) function. By using this function, the ECU automatically shuts down and restarts the internal combustion engine to reduce the amount of time the engine spends idling, thereby reducing fuel consumption and emissions.
In particular, content of the roadmap of engine manufacturers, aimed to reduce fuel consumption and carbon dioxide (CO2) emissions, is the extension of the “Stop & Start” potential using a “soft electrification” to meet Corporate Average Fuel Economy (CAFE) target, foreseen in 2020. CAFE are regulations in the United States, intended to improve the average fuel economy of cars and light trucks. An extended use of the “Stop & Start” function is realized, by stopping the engine not only if the vehicle speed is zero, but also if the vehicle is slowing down, practically when the vehicle speed is lower than a predetermined threshold. The enhanced S/S during coasting phase is called “Sailing”. In other words, there is an ability of the vehicle to shut-off the engine at high vehicle speed, for example at 120 kph or about 75 mph.
In some situation, using the “Sailing” function can decrease drivability and handling of the vehicle. In fact, while during straight driving and flat road condition there is no issue; in real driving conditions the engine shutoff at high vehicle speed may not be desirable. Therefore, a need exists for a new method of controlling an automatic engine stop, which enables the “Sailing” function avoiding the above problems.